Damping means for magnetic reed contact



A ril 14, 1964 BERGSTRASSER 3,129,311

DAMPING MEANS FOR MAGNETIC REED CONTACT Filed March 26, 1962 /NVEN70/P W W M WWW KW United States Patent 3,129,311 DAMPING MEANS FOR MAGNETIG REED CGNTACT Georg Bergstriisser, Frankfurt am Main, Germany, as-

signor to Telefonhau and Normaizeit G.m.b.H., Frankfurt am Main, Germany, a firm of Germany Filed Mar. 26, 1962, Ser. No. 182,411 Claims priority, application Germany May 20, 1961 13 Claims. (Cl. 209-166) This invention refers to switching structures adapted to be controlled by magnetic fields.

It is a general object of this invention to provide improved switching structures of the above description.

It is another object of this invention to provide simple and compact switching structures suitable for application in communication engineering having contacts capable of positively opening and closing electric circuits, i.e. having contacts not subject to mechanical oscillations or vibrations during the opening stroke and during the closing stroke thereof.

Still another object of this invention is to provide an improved version of the switching structures disclosed in the copending patent application of Georg Bergstrasser et al., filed June 15, 1960, Ser. No. 36,268 for Switching Contact Controlled by Magnetic Field, now US. Patent 3,067,304 issued Dec. 4, 1962.

A further object of this invention is to provide switching structures adapted to be controlled by magnetic fields with simple and effective damping means for suppressing oscillatory or vibratory motions tending to occur at a natural frequency.

A further object of this invention is to provide switching structures adapted to be controlled by magnetic fields with damping means which do not significantly increase the reluctance of the path of the magnetic flux through such structures, and thus do not call for a relative increase of the intensity of the magnetic field required for operating the switching structures.

This invention is more particularly concerned with switching structures comprising a pair of relatively flat cooperating switching elements of magnetizable material arranged substantially in a common plane, at least one of said pair of elements having a zone of reduced crosssection imparting freedom of relative motion within said common plane to portions of said one of said pair of elements situated to opposite sides of said zone of reduced cross-section. In such an arrangement magnetic energization of the two switching elements, i.e. passage of a magnetic flux through said pair of elements, causes engagement of juxtaposed edges of said pair of elements. This, in turn, causes a pair of cooperating contact surfaces to either engage, to close an electric circuit, or to disengage, to open an electric circuit. Upon de-energization of the switching structure, i.e. cessation of a magnetic flux extending through the cooperating switching elements, one of the elements is pulled out of engagement with the other element by separating means for said elements. The separation of the aforementioned switching elements may either cause disengagement of a pair of cooperating contact surfaces which are normally closed, or closing of a pair of cooperating contact surfaces which are normally open. The relatively movable magnetizable switching elements and contacts involve mass and constitute an oscillatory system having a natural frequency. Therefore separation of the aforementioned switching elements and contact surfaces tends to be followed by an oscillatory motion which results in a series of highly undesirable periodic closings and/or openings of the circuit under the control of the switching structure. This drawback is sometimes referred-to as contact bounce.

3,129,311 Patented Apr. 14, 1964 It is a prime object of this invention to provide switching structures wherein an opening of the circuit to be interrupted is not followed by a temporary unintentional re-closing thereof and wherein a closing of a circuit to be closed is not followed by a temporary unintentional re-opening thereof.

The foregoing and other general and special objects of the invention and advantages thereof will more clearly appear from the ensuing particular description of the invention, as illustrated in the drawing, wherein-- FIG. 1 is substantially a longitudinal section of a magnetic relay embodying the invention, some of the parts thereof being shown in front elevation rather than in section;

FIG. 2 is a cross-section of the structure shown in FIG. 1;

FIG. 3 is substantially a longitudinal section of another magnetic relay embodying this invention, some of the parts thereof being shown in front elevation rather than in section; and

FIG. 4 shows the same structure as FIG. 3 in the same fashion as FIG. 3 and differs from FIG. 3 by the addition of highly effective damping means for suppressing relative oscillatory or vibratory motions of the contact surfaces.

Referring now to the drawing, and more particularly to FIGS. 1 and 2 thereof, reference numerals 12 and 13 have been applied to indicate a pair of relatively flat cooperating switching elements of a resilient magnetizable material substantially in the shape of elongated strips or stampings arranged in a common plane, or substantially in a common plane. At least one of said pair of elements has a zone of reduced cross-section 16 imparting freedom of relative motion within said common plane to portions of said one of said pair of elements situated to opposite sides of said zone 16 of reduced cross-section. As shown in FIG. 1 the zone of reduced cross-section is substantially in the shape of a sinusoidal web 16. If desired switching element 12 may be provided with a like zone of reduced cross-section, as more fully disclosed in the aforementioned patent application Ser. No. 36,268. Elements 12 and 13 have juxtaposed oblique edges 14 and 15 which may be used as contact surfaces for closing and opening an electric circuit. The axially outer ends of switching elements 12, 13 form solder lugs for inserting switching elements 12, 13 into an electric circuit. If a magnetic flux is caused to flow in a direction generally longitudinally of elements or strips 12 and 13, the portion 17 of element 13 to the right of web 16 is caused to move within the common plane defined by elements 12, 13 from the position shown in FIG. 1 to the right. This results in cooperative engagement of edges or contact surfaces 14, 15 and closing of an electric circuit. Web 16 operates as a spring retracting portion 17 and its edge 15 from edge 14 upon de-energization of the magnetic circuit whose flux extended through parts 12, 13 in a direction substantially longitudinally thereof. The spring action inherent in web 16 and the mass inherent in portion 17 of element 13 constitute an oscillatory system having a given natural frequency. There is virtually no tendency of contact bounce when edges 14 and 15 engage under the action of a magnetic field. However, there is a strong tendency for part 17 to perform oscillatory motions when elements 12, 13 are de-energized, and edge 15 moves away from edge 14 under the bias of resilient web 16. In order to suppress said oscillatory motion, portion 17 of element 13 is provided with a damping mechanism including a perforation or window 18 and damping means 19, 20 in form of rollers loosely arranged within said window or perforation 18. Elements 12, 13 are arranged in a housing 11 which may be made of glass and in which case elements 12, 13 are sealed into the housing thereof. Rollers 19, 29 are adapted to be engaged by the inner walls 21 of housing 11 and thus are maintained within perforation or window 18. Rollers 19, 20 are held in position by the edges of perforation or window 18 which form the perimeter of perforation or window 18 and which are, in substance, formed by a line closed in itself. On the other hand rollers 19, 20 are held in position by the inner surfaces of the walls 21 of housing 11. The magnetic field for energizing magnetizable elements 12, 13 may be established by a coil 40 mounted on housing 11.

At each movement of portion 17 of element 13 the rollers 19, 20 are dragged with it and dampen the tend ency thereof to oscillate. It will be apparent that rollers 12, 13 being loosely inserted into window 18 do not form part of the oscillatory switching system which includes the contact surface or edge 15. Loose insertion means in this context that there is a clearance between rollers 19, 2t and the edges of window 18 allowing rollers 19, 2th to move slightly relative to portion 17 of switching element 13. Rollers 19, 20 have a given moment of inertia and a given natural frequency. The natural frequency in which rollers 19, 20 tend to oscillate differs from the natural frequency of the oscillatory system 16, 17, and the phase angle of the oscillations of rollers 19, 29 differs from the phase angle of the oscillations of the oscillatory system 16, 17, and thus oscillations of the latter are being damped by oscillations of rollers 19, 20. Thus oscillatory system 16, 17 is rendered aperiodic. By properly designing rollers 19, 20 any oscillatory motion of the oscillatory system 16, 17 at its natural frequency may be virtually entirely suppressed. As suggested above the effectiveness of rollers 19, 20, or of equivalent damping bodies within perforation 18, depends upon the looseness of the mechanical coupling with the oscillatory system 16, 17.

The friction between any damping body 19, 20 and the internal surface 21 of housing 11 should be minimized in order not to limit the speed of movement and/or the acceleration of portion 17 and contact surface 15 under the action of a magnetic field of coil 40.

The rollers 19, 20 or other damping bodies loosely inserted into perforation or window 18 should preferably be made of a magnetizable material in order not to substantially increase the reluctance of the path of the magnetic flux through element 13 by virtue of the presence of the perforation or window 18 in its right hand end portion 17.

FIG. 1 refers to an arrangement comprising a pair of contact surfaces 14, 15 which are and remain closed as long as a predetermined magnetic flux is maintained through parts 12, 13. In that instance the electric circuit through contacts 14, 15 is opened upon magnetic de-energization of parts 12, 13, and there is a tendency of reclosing of that circuit by virtue of oscillatory motions of the oscillatory system 16, 17. The aforementioned damping means avoid that danger.

The aforementioned damping means may also be applied to structures of the same kind as shown in FIGS. 1 and 2 but having contact surfaces adapted to open an electric circuit when the magnetizable switching elements are magnetically de-energized. Such structures have been shown more in detail in the aforementioned patent application Serial No. 36,268, and reference may be had to that application for a more complete disclosure of such structures. In structures of the above kind wherein a pair of cooperating contact surfaces is caused to engage and to thereby close an electric circuit upon de-energization of a pair of magnetizable switching elements there is a tendency of contact bounce upon magnetic de-energization, i.e. a tendency for one or both cooperating contacts to oscillate and to thereby periodically re-open and re-close the circuit into which the contact surfaces are inserted. It is apparent that this drawback can be elimi nated by providing such switching structures with damping means of the kind illustrated in FIGS. 1 and 2 and described in connection therewith.

Magnetic relays of the kind shown in FIGS. 1 and 2 may also be adapted as change-over-relays, as more fully explained in the aforementioned patent application Serial No. 36,268, now Patent No. 3,067,304 and in such changeover-relays undesirable mechanical oscillations and consequent periodic openings and closings of the circuits controlled by the relays may be suppressed by damping means of the character illustrated in FIGS. 1 and 2, and described in connection therewith.

It will be noted that housing 11 is relatively flat and that its cross-section is approximately rectangular. Thus the internal walls 21 of housing 11 lend themselves particularly well to form abutments for maintaining rollers 19 and 20 in position within window 18.

The structure of FIG. 3 is an improvement over the structure of FIGS. 1 and 2 inasmuch as in the former the reluctance of the path of the magnetic flux tends to be relatively less than in the latter. The structure of FIG. 3 does not include any means for damping oscillations engendered upon cessation of a magnetic flux through the magnetizable elements of the structure. This structure is, however, particularly well adapted to be combined with such damping means. FIG. 4 shows the same structure as FIG. 3 upon addition of such damping means to it.

In FIGS. 3 and 4 mainly the same reference characters have been applied to indicate like parts as in FIGS. 1 and 2, however, with a prime sign added to the reference characters.

Referring now to FIG. 3, a housing or envelope 11 of glass having substantially the same cross-section as shown in FIG. 2 accommodates a pair of switching elements 12', 13' of a resilient magnetizable material. Elements 12', 13 are sealed into envelope 11'. Their axially outer ends project outside of envelope 11' and form perforated solder lugs for securing wire leads to elements 12', 13'.

Switching element 12' is provided with a first lateral incision 27', 30' having a relatively narrow open entrance region 27 and a closed end region 30' which is relatively Wide in a direction longitudinally of parts 12, 13'. Switching element 12' is further provided with a second lateral incision 28', 29' having a relatively narrow open entrance region 28' and a closed end region 29' which is relatively wide in a direction longitudinally of parts 12, 13'. The entrance regions 27, 28 are situated on opposite sides of switching element 12. Each of both incisions 27, 30' and 28', 29 is substantially in the shape of a rectangular dead-end street and incisions 27', 30' and 28' 29 define jointly a substantially S-shaped web of small cross-sectional area mechanically connecting the right end portion 26' of switching element 12' to the left 7 end thereof. The aforementioned S-shaped web is highly resilient and performs basically the same function as web 16 of the structure of FIGS. 1 and 2, i.e. it imparts freedom of relative motion between the right and the left end of switching element 12' within the plane defined by switching elements 12', 13'. The S-shaped web structure of FIG. 3 tends to have a. considerably smaller magnetic reluctance than the substantially sinusoidal web structure shown in FIG. 1. This is due to the fact that the webstructure of FIG. 3 includes three web elements extending in a direction longitudinally of switching elements 12', 13 and that the open entrance portions 27', 28 form extremely narrow flux-shunting air gaps whose magnetic reluctance is correspondingly low. The width of the S-shaped web structure of FIG. 3 as well as the width of the sinusoidal web 16 of FIG. 1 may be in the order of the thickness of the switching element 13 and 12', respectively, of which they form an integral part. As a result of the decrease of the reluctance of the flux path of the structure of FIG. 3 relative to that of the flux path of the structure of FIG. 1 a relatively smaller number of ampere turns is required to operate the structure of FIG. 3. The structure of FIG. 3 is intended to be provided with a magnetic energizing winding in the same fashion as the structure of FIG. 1, but such a winding has been omitted in FIG. 3.

The incisions 2'7, 30' and 28, 29' of the structure of FIG. 3 form spaces which are particularly well adapted to receive damping inserts and, therefore, the structure of FIG. 3 does not require the provision of an additional perforation in the nature of the rectangular opening 18 shown in FIG. 1 for accommodating therein loosely arranged damping means.

FIG. 4 illustrates how damping means in the shape of elongated cylindrical rollers 31, 32' can be arranged in incisions 27, 30' and 23', 29 or, to be more specific, in the relatively wide closed end regions 3t), 29 of incisions 27, 30' and 23, 29'. It will be understood that rollers 31, 32' of the structure of FIG. 4 will be held in position by the inner surfaces of housing 11' in the same fashion as rollers 19, 20 in the structure of FIGS. 1 and 2. Rollers 31, 32 are preferably made of a magnetizable material. Thus the cross-section of the flux path inside of magnetizable material is greatly increased and the path of the flux in non-magnetizable material is limited to the very narrow air gaps whose magnetic reluctance is minimal.

As shown in FIG. 4 the closed end portions 30' and 29 of incisions 27, 3t) and 28, 29 may be provided with axial extensions 34' and 33'. Rollers 32 and 31' project into these extensions 3 33' and the latter define shoulders jointly with the entrance portions 27', 28' maintaining the rollers 32, 31 in proper axial alignment. Another pair of such shoulders is formed by open en trance portions 2'7, 28' and closed end portions 3d, 29.

It will be understood that I have illustrated and described herein preferred embodiments only of the invention, and that various alterations may be made in the details thereof Without departing from the spirit and scope of the invention as defined in the appended claims.

I claim as my invention:

1. A switching structure controlled by magnetic field action comprising:

a pair of cooperating switching elements of magnetizable material arranged substantially in a common plane, at least one of said pair of elements having a zone of reduced cross-section imparting freedom of relative motion within said common plane to portions of said one of said pair of elements situated to opposite sides of said zone of reduced cross-section, one of said portions of said one of said pair of elements defining a perforation;

a pair of cooperating contact surfaces selectively engaged and disengaged by said relative motion of said portions of said one of said pair of elements;

a housing enclosing said pair of elements and having an inner wall;

and damping means loosely arranged within said perforation engaged by said inner wall of said housing and maintained within said perforation by said inner wall of said housing.

2. A switching structure as specified in claim 1 wherein said damping means consist of magnetizable material.

3. A switching structure as specified in claim 1 wherein said damping means comprise cylindrical rollers.

4. A switching structure as specified in claim 1 wherein said pair of elements is formed by a pair of elongated strips of magnetizable material, and wherein said damp- 6 ing means are formed by a pair of cylindrical rollers both oriented in a direction longitudinally of said pair of strips.

5. A switching structure as specified in claim 1 wherein said perforation has a perimeter which is a line closed in itself.

6. A switching structure as specified in claim 1 wherein said perforation is formed by incision means defining said zone of reduced cross-section and wherein said incision means have a relatively narrow open entrance region and a relatively wide closed end region.

7. A switching structure controlled by magnetic field action comprising:

a pair of elongated substantially flat cooperating switching elements of magnetizable material arranged substantially in a common plane, at least one of said pair of elements having incision means imparting freedom of relative motion within said common plane to portions of said one of said pair of elements situated to opposite sides of said incision means;

a pair of cooperating contact surfaces selectively engaged and disengaged by said relative motion of said portions of said one of said pair of elements;

a housing enclosing said pair of elements and having an inner wall;

and damping means loosely arranged within said incision means and engaged by the inner wall of the housing and maintained within said incision means by said inner wall of said housing.

8. A switching structure controlled by magnetic field action comprising:

a pair of elongated substantially fiat cooperating switching elements of magnetizable material arranged substantially in a common plane, at least one of said pair of elements having a zone of reduced crosssection imparting freedom of relative motion within said common plane to portions of said one of said pair of elements situated to opposite sides of said zone, said zone including a plurality of web sections extending preponderantly in a direction longitudinally of said pair of elements;

a pair of cooperating contact surfaces selectively engaged and disengaged by said relative motion of said portions of said one of said pair of elements;

a housing enclosing said pair of elements and having aninner wall;

and damping means of magnetizable material loosely arranged in interstices defined by said plurality of web sections and engaged by said inner wall of said housing and maintained within said interstices by said inner wall of said housing.

9. A switching structure controlled by magnetic field action comprising:

a pair of elongated substantially flat cooperating switching elements of magnetizable material arranged substantially in a common plane, at least one of said pair of elements having a pair of lateral incisions imparting freedom of relative motion within said common plane to portions of said one of said pair of elements situated to opposite sides of said pair of incisions, each of said pair of incisions having a relatively narrow open entrance portion and a relatively wide closed end portion extending in a direction substantially longitudinally of said pair of elements, said pair of incisions jointly defining a substantially S-shaped zone of reduced cross-sectional area between said portions of said one of said pair of elements;

a pair of cooperating contact surfaces selectively engaged and disengaged by said relative motion of said portions of said one of said pair of elements;

a housing enclosing said pair of elements and having an inner Wall;

and a pair of damping means of magnetizable material each arranged within said wide closed end portion of one of said pair of incisions and engaged by Said inner Wall of said housing and maintained within said pair of incisions by said inner wall of said housing.

10. A switching structure as specified in claim 9 wherein said pair of damping means consists of a pair of elongated cylindrical rollers oriented in a direction longitudinally of said pair of elements.

11. A switching structure as specified in claim 9 wherein the length of said closed end portion of each of said pair of incisions in a direction longitudinally of said pair of elements is a multiple of the width of the air gap formed by said open entrance portion of each of said pair of incisions.

12. A switching structure as specified in claim 9 wherein said closed end portion of each of said pair of incisions and said open entrance portion of each of said pair of incisions defines a pair of shoulders for maintaining one of said pair of damping means in a position longitudinally of said pair of elements.

13. A switching structure controlled by magnetic field action comprising:

a pair of elongated substantially flat cooperating switch- 8 ing elements of magnetizable material arranged substantially in a common plane, at least one of said pair of elements having a pair of incisions each in an opposite longitudinal edge thereof, each of said pair of incisions having a relatively narrow open entrance portion and a relatively wide closed end portion extending in a direction substantially longitudinally of said pair of elements, said pair of incisions jointly defining a substantially S-shaped Web of reduced cross-section imparting freedom'of relative motion within said common plane to portions of said one of said pair of elements situated to opposite sides of said S-shaped Web;

and a pair of cooperating contact surfaces selectively engaged and disengaged by said relative motion of said portions of said one of said pair of elements.

Masheris et a1 Feb. 23, 1954 Bergstrasser et a1. Dec. 4, 1962 

1. A SWITCHING STRUCTURE CONTROLLED BY MAGNETIC FIELD ACTION COMPRISING: A PAIR OF COOPERATING SWITCHING ELEMENTS OF MAGNETIZABLE MATERIAL ARRANGED SUBSTANTIALLY IN A COMMON PLANE, AT LEAST ONE OF SAID PAIR OF ELEMENTS HAVING A ZONE OF REDUCED CROSS-SECTION IMPARTING FREEDOM OF RELATIVE MOTION WITHIN SAID COMMON PLANE TO PORTIONS OF SAID ONE OF SAID PAIR OF ELEMENTS SITUATED TO OPPOSITE SIDES OF SAID ZONE OF REDUCED CROSS-SECTION, ONE OF SAID PORTIONS OF SAID ONE OF SAID PAIR OF ELEMENTS DEFINING A PERFORATION; A PAIR OF COOPERATING CONTACT SURFACES SELECTIVELY ENGAGED AND DISENGAGED BY SAID RELATIVE MOTION OF SAID PORTIONS OF SAID ONE OF SAID PAIR OF ELEMENTS; A HOUSING ENCLOSING SAID PAIR OF ELEMENTS AND HAVING AN INNER WALL; AND DAMPING MEANS LOOSELY ARRANGED WITHIN SAID PERFORATION ENGAGED BY SAID INNER WALL OF SAID HOUSING AND MAINTAINED WITHIN SAID PERFORATION BY SAID INNER WALL OF SAID HOUSING. 